We are working on a project involving poplar boards and we are having issues with our onsrud 57-910 1/4" downcut bits breaking on multiple occasions. We've talked to onsrud a few times and verified our feeds and speeds according to their chip load calculations and we still are having issues. The last suggestion they had was to purchase a torque wrench to make sure we aren't over-tightening the collet nut but I don't want to spend the money on a torque wrench if it's not necessary. We haven't had this problem with any other material but the poplar, if anyone has suggestions I would really appreciate it.
Feeds and speeds:
18,000 RPM
.75" thick poplar with .25" cutting depth on each pass
3.4 in/sec
Thanks
-P